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“From our point of view, the defining issue of the moment is the crisis of the middle class and the explosion of inequality where the rules are rigged by the 1 percent and Wall Street to the detriment or ordinary Americans,” said Ben Wikler, the Washington director of the online organizing outfit MoveOn.org.

He was explaining why his group, a venerable institution in the Netroots of the progressive movement, was raising $1 million in order to draft Elizabeth Warren into the presidential race.

“We want candidates and voices in the mix in the 2016 primary will speak to the need to fight for working-class people, and to change the system so that it works for everyone.”

Throughout the progressive movement, this sentiment is echoed almost everywhere. “Hands down she is the best messenger,” said Charles Chamberlain, executive director of Democracy for America, an organizing group that grew out of the ashes of Howard Dean’s 2004 presidential campaign. Citing a long list of progressive priorities, including lowering student debt and raising the minimum wage, he said that “It is vital that she run.”

In New York City on Thursday, dozens of activists marched on Citigroup’s headquarters in lower Manhattan to push for the restoration of some of the components of the Dodd-Frank bank-reform bill, legislation that helped bring Warren to national prominence. The point of the march? “To amplify Elizabeth Warren’s message,” according to organizers.

But it is an odd thing about those Democrats looking for a liberal alternative to Hillary Clinton—there already is a fire-breathing liberal in the presidential race (or inching toward it, at least) someone who has spent decades railing against the powers that be.

Bernie Sanders, the junior senator from Vermont is a self-described socialist who has, unlike Warren, actually been making the rounds in the early primary states of Iowa, New Hampshire, and South Carolina. At an event in Iowa this week, Sanders called for a “political revolution,” single-payer health care, universal pre-K, and “a real struggle against the billionaire class.”

Also this week, he keynoted a fundraiser for Progress Iowa, an influential liberal group in the first-in-the-nation caucus state. Around 180 people showed up, while a few nights later, MoveOn hosted a Draft Warren party; the Massachusetts senator wasn’t there, but there were still around 80 people in attendance. When asked how many people would have shown up to his fundraiser had it been hosted by Warren and not Sanders, Matt Sinovic, the executive director said, “My guess is there would be a lot more.”

“There might be a ‘new fresh thing’ going on here,” said Thom Hartmann, a liberal radio host and Sanders supporter. But he also raised another concern echoed by many in the progressive movement who have explained why they are supporting the candidate who has said she is not running over the one who is.

“Among progressives, I think one of things that makes them inclined toward Elizabeth Warren is that, let’s face it, Bernie is a white guy and she is a woman. Having an African-American [president] was historic, and having a woman would be historic, too,” he said. “There is too much testosterone in American politics. Bernie acknowledges that.”

Hartmann added that among Sanders supporters, the quietly whispered conspiracy rumor was that progressive groups were trying to lure Warren into the race just as Sanders was gaining traction as a way to stymie his momentum and get a chit from the Clintons. MoveOn, after all, grew out of the Clinton impeachment proceedings, and Dean, the inspiration for Democracy for America, has said he is ready for Hillary Clinton. (This scheme could not, ahem, be independently verified.)

Others say that the reason Sanders has ignited the left in the same way that Warren has is that Sanders is something of a full-spectrum liberal—climate change, campaign-finance reform, inequality, infrastructure spending, worker-run cooperatives, surveillance, genetically modified foods, a humbler foreign policy. Warren is more of a single-note singer—inequality, and the way the economic system is rigged to produce more of it—and it’s a note she sings over and over again. And it is also one that happens to hit the cultural moment exactly, a moment that includes Occupy Wall Street and a best-seller devoted to the subject by a previously obscure French economist.

Some of this political capital should be Sanders’ for the taking. He first rose to national prominence during an eight-hour filibuster on the floor of the Senate in 2010, in which he railed against a deal that the Obama administration cut with congressional Republicans to extend the Bush-era tax cuts for upper-income earners.

Aides and supporters to Sanders insist that he remains unbothered by Warren’s ascension.

“It’s not the least bit frustrating,” said Tad Devine, the political operative and vet of both Al Gore and John Kerry’s presidential campaigns, and who is now working for Sanders. “She has said she is not running.”

“She is a very appealing candidate in the way she talks about these things,” Devine said. “She connects.” But he recalled 1991, when the political world was waiting for Mario Cuomo to take his chartered jet to New Hampshire and enter the race. “You have to get in if you want that message to get heard.”

But, Devine said, the groundswell for Warren would translate into support for Sanders once the campaign began, and he was in and she was out.

“People who want the party to go in a different direction than it would under Hillary Clinton’s leadership are looking for someone to nominate,” he said. A Warren challenge to Clinton, he added, would be predictable, playing out much as Barack Obama’s did to her in 2008, with the big money forces evenly divided.

Sanders, on the other hand, would change the usual playbook, by “bringing people who have been on the fringes into the grain of American politics, people who haven’t participated because they don’t think they are going to get anything out of it or they don’t see anybody who represents their ideals.”

Sanders hasn’t declared his candidacy either, Devine pointed out, and since he is not a registered Democrat, voters aren’t yet sure what to make of him.

“He hasn’t established his identity as a Democrat yet. They look at him and wonder, ‘Is he another Ralph Nader? Will he run as an independent? Where does he fit into the process?’”

But if some progressives and progressive groups aren’t embracing Sanders, it is also in part because despite his liberal leanings, he never much embraced the movement. In the midterms, for example, Warren was a powerhouse, not just traveling to red states like Kentucky to campaign for Democrats, but hosting conference calls with activists urging them to get out the vote and lending her name to email appeals.

The progressive universe rallied behind Warren back when she was vying to become the head of the Consumer Finance Protection Bureau. When that bid failed, progressive groups flocked to Massachusetts to help her defeat Scott Brown and gain a seat in the U.S. Senate.

“She understands that she is part of this movement, and that she is helping to lead it,” said one organizer. “Bernie doesn’t have an interest in being a part of any movement. He doesn’t play nice.”

“He is a lifetime politician,” said one D.C.-based consultant. “He doesn’t understand new media or online organizing. Elizabeth comes out of that movement. She has been working for progressive activists for a dozen years before coming to national prominence.”

Last year at Netroots Nation, an annual event for progressive activists to trade notes and tips, Warren lit up the stage, telling the crowd that “The game is rigged!” over cries of “Run Liz Run!”

Sanders, meanwhile, has never addressed the group.

Raven Brooks, the executive director of Netroots Nation, said of Warren, “Look at the amount of money she generates. Look at how much attention she is able to generate for her ideas.”

She is able to create coattails for down-ballot races and to change the narrative frame of politics. For Sanders to do that, he said, “he would have to embrace a radically different form of politics.”

If Brooks had to name the people he would most want to see run for president, Sanders would not be anywhere close to the top of the list.

“Guys like Bernie and Dennis Kucinich, I love guys like that. I just don’t think they are very effective at getting stuff done. Running for president isn’t just about running for office. It is about how many people you can take with you.”

Sanders remains overwhelmingly popular in his home state of Vermont, and when he was running for re-election, activists from the Working Families Party tried to get him to run on their line. The WFP had emerged as the primary organizing force for liberals in states throughout the Northeast, acting as a Good Housekeeping seal of approval for progressives. Sanders, however, the avowed independent, declined.

“He is ‘an independent socialist,’” said one organizer supportive of Warren. “That is an important messaging choice. And it tells you all you need to know about where he sees himself in the movement.”